Radio Frequency Changes Abend FS9

On three separate occasions, I have switched between radio frequencies and FS9 has aborted. I press the button to switch to newly dialed frequency, and the screen goes black. the hard drive starts 'crunching' and FS9 dies.This only happens with the 737TNG and seems to be independent of the-600 or -700 models.Anyone else seen this or have ideas?Thanks